A method has been developed to tune the electronic property of zinc-oxide thin-film transistors (TFTs) by annealing them in different gases. The experiments show that annealing in air increases the threshold voltage of the TFTs, while annealing in nitrogen gas reduces it. The zero-bias conductivity can be changed by nearly six orders of magnitude. With a combination of annealing in air and nitrogen it is hence possible to tune the threshold voltage over a wide range of pre-determined values to satisfy different circuit applications. The annealed devices also show good stability over a 25-day period in ambient air without encapsulation. The effects on other performance parameters of the TFTs and possible physical mechanisms are discussed. (C) 2013 Elsevier B.V. All rights reserved.